Magnetic conductive members of stators or rotors of electrical machines will, in the near future, be increasingly made of SMC material (soft magnetic powder iron composite), and will replace laminated core assemblies or laminated cores, since, from a manufacturing technology point of view, they are much more simple to produce. The SMC material is pressed into the desired shape using a pressing mold, and is then heat treated at a relatively low temperature, so that the necessary insulating layers between the powder particles are not destroyed.
In one known multipolar stator made of SMC material for an internal-rotor machine (PCT International Publication No. 99/50949) the outer-lying magnetic yoke is composed of a number of yoke segments corresponding to the number of poles of the stator poles. Each yoke segment carries in one piece a stator pole having a pole core and a pole shoe bordering the pole core at the latter's remote end. Each yoke segment along with pole core and pole shoe is produced from SMC material by pressing and heat treating. The pole cores are rounded off at their axial ends or have an oval profile, so that, as a result of the removal of sharp edges at the pole cores, only a thin insulating layer has to be applied, onto which the pole winding may then be wound. The individual pole windings of the stator winding are wound directly onto the pole cores, using the usual machine-based winding technology. After winding the pole windings, the individual yoke segments are set next to one another in the circumferential direction and are fixedly connected to one another.
In the case of another known stator made of an SMC material for an internal-rotor motor (PCT International Publication No. 00/69047), the ring-shaped magnetic yoke on the one hand, and the stator pole having pole core and pole shoe on the other hand, are made separately of SMC material in the desired shape. After sliding the pole windings, prefabricated as ring coils, onto the pole cores, the stator poles are set into prepared recesses in the magnetic yoke with form locking, with the ends of the pole cores that are at a distance from the pole shoe, and are fastened there.